Inhibitory Effect of Calcium Phosphate-Coated High-Affinity Liposomes on Staphylococcus Aureus and its Biofilms

The contamination of Staphylococcus aureus (S. aureus) and its biofilm poses a serious challenge to food safety. In this study, a high-affinity liposome coated with calcium phosphate was developed to provide a novel strategy for antibacterial packaging. Litsea cubeba essential oil (LC-EO)-loaded liposomes with various anionic surfactants including sodium deoxycholate (SDC), sodium dodecyl sulfate (SDS), and sodium dodecyl benzene sulfonate (SDBS) were first synthesized using a film-ultrasonic dispersion method, then an attempt was made to coat calcium phosphate (CaP) shell layers on the surface of different anionic liposomes using a sequential deposition method. Anionic liposomes synthesized with the addition of SDBS (SDBS/EO-Ls) were found to be effective precursors for the successful capping of CaP shells. The SDBS/EO-Ls coated with CaP shells (CaP/SDBS/EO-Ls) were then characterized, including physicochemical properties, stability, and antibacterial and anti-biofilm activities. Results showed that the particle size of SDBS/EO-Ls can be increased by about 40 nm after being coated with a CaP shell, and the Zeta potential value can be decreased by about 25 mV. At the same time, the CaP coating helped to prevent the leakage of essential oils during storage. The prepared CaP/SDBS/EO-Ls had a better inhibitory effect against S. aureus and biofilm due to their high affinity. Even when CaP/SDBS/EO-Ls were applied in two different food systems (smoked bean curd and beef), they still had a long-lasting antibacterial effect. The CaP/SDBS/EO-Ls developed in this study could be used to develop a novel antimicrobial packaging additive.